Radio signals, whether they come from a standard one-way radio or a two-way radio (such as a cellular phone) can be disrupted or jammed using a jamming device. A jamming device transmits on the same frequency as the radio in order to prevent a receiver from successfully recovering a radio signal. Disrupting communication between a radio and a receiver may be done using various techniques. For example, the jamming device may overpower the radio by transmitting a signal on the same frequency at a high enough power and for a long enough time that the noise or interference created by this jamming device will prevent the victim receiver from successfully recovering its intended signal.
Some jammers are tuned to block only one frequency, others block a group of frequencies or a sub-band, and yet others can block several types of networks at once or all frequencies in a frequency band. Selecting only some frequencies to jam in the hope of generating high enough noise levels at the victim receivers or in order to not disrupt friendly communication channels leaves an area vulnerable to hostile signals using other frequencies or traveling on other frequencies to escape jamming. However, effectively blocking all frequencies of a given band will not allow friendly signals to be received, essentially cutting off all friendly communications for that area.
Therefore, there is a need for a system that can block hostile signals from all frequencies across a given frequency band, while still allowing friendly signals to be received on these same frequencies.